Process for preparing beta-amino-anthraquinones



Patented May 23, 1933 STATES IVAN GUBELMANN AND JOHN M. TINKER, OF SOUTHMILWAUKEE, WISCONSIN, ASSIG-IIOES, BY MESNE ASSJ-GNMEIQTS, TO E. I. DUFONT DE NEMOUBS & COMPANY,

A CORPL'RATION 03F DELAWARE EROCESS F03 PREIARINGBETA-AMINO-ANTHBAQUINONES No Drawing.

This invention relates to the preparation of beta-amino-anthraquinoneand more particularly to an improvement in the process of manufacturingthis compound by treating a beta-anthraquinone-sulfonic acid compoundwith ammonia.

Beta-amino-anthraquinone is a commercially important product in that itis a very valuable intermediate for the preparation of certaindyestuffs. Its value in this regard, lOWGVGl, is often directlydependent upon its state of purity.

Of the methods for making beta-aminoanthraquinone, that involving thereplace ment of the sulfo group in betaanthraquinone-sulfonic acid bymeans of ammonia has found the greatest commercial application. Variousmodifications of this general process have been devised in an attempt toproduce a high grade beta-amino-anthr aquinone in a commerciallyfeasible manner.

The f llowing specific modifications of said I general method aredisclosed in the l1tera-.

ture; the treatment of betaanthraquinonesulfonic acid with aqueousammonia under high temperature and pressure, without the addition of anyother substances thereto; a similar treatment of thebeta-anthraquinonesulfonic acid but in the presence of oxidizing agentssuch as sodium bichremate, potassium chromate, manganese dioxide,cuprous or cupric oxide, arsenic oxide, silver oxide, copper sulfate andpotassium bromate; the heating of beta-anthraquinone-sulfonic acid withammonia under pressure as above but in the presence of inorganic saltssuch as barium, calcium and magnesium salts; and a treatment ofbeta-anthraquinonesulfonic acid under pressure with ammonia as disclosedabove but in the presence of aryl-nitro compounds such as intro-benzene,nitro-toluene, nitro-naphthalene, or their sulfonic acids and salts.

Each of these processes, however, possess certain objectionable featureswhich reduce its desirability and efficiency for commercial application.Thus, the methods wherein no oxidizing agents are employed generallygive very poor yields, usually reported to be about 19 to 45% of theory.On the other hand,

1930. Serial No. 461,043.

.ficult.

We have now found tha if'beta-anthraquinone-sulfonic acid, or a saltthereof, be treated with aqueous ammonia at elevated temperatures, underpressure, and in the presence of an oxidizing agent, but under suchconditions as to avoid the presence of an excess of oxidizing agent atany given instant, bet-a-amino-anthraquinone is obtained not only inhigh yield but in an exceptional state of purity as compared to hithertoknown methods. With this process, moreover, it is merely necessary tofilter the solid beta-amino-anthraquinone produced therein from thereaction liquors, to obtain a product highly adapted for direct use asan intermediate in the preparation of various dyestuffs, such forexample as indanthrone or fhwanthrone.

It is accordingly an object of this invention to provide a process forproducing betaamino-anthraquinone in good yields and in a high state ofpurity.

It is a further important object of this invention to provide a processfor preparing beta-amino-anthraquinone that is highly economical,simple, readily controllable and requires no special degree of skill onthe part of the operator to carry it to completion.

Itis a further important object of this invention to provide a processfor producing beta-amino-anthraquiilone in good yields and in a highstate of purity by heating betaanthraquinone-sulfonic acid and ammoniato their reaction. temperature and slowly adding an oxidizing agent tothe reaction mixture.

It is a further important object of thi= invention to provide a processfor preparing beta-amino--anthraquinone o l great purity and in goodyields by heating together betaanthraquinone-sul'l onic acid and ammoniato effect a reaction therebctween and then adding an oxidizing agent tothe reaction mixture at a rate connnensurate with the rate of formationof suli urous acid. in said n'iixture.

Other and further important obj of this invention will become apparentfrom. the following description and appended claims.

()nr method consists n'ieliy in charging antliraquinone-beta-sultonicacid or its salts into an autoclave containing an excess of aqueousammonia, and heating the mass to the preferred reaction temperaturewhich is generally around 100 to 210 C. lVe then gradually introduce asolution or suspension of an oxidizing agent into the reaction mass, ata rate comparable to the rate of reaction. Another way of expressingthis is to say that we add the oxidizing agent at a rate not substantially higher than the rate of formation of sulfurous acid. The rate01 reaction varies with the temperature and pressure. At the highertemperatures the amidation may be completed in 5 to Ghours. T helo u'erten'iperatures may require as long a treatment period as 24- hours. l vetherefore regulate the supply oi": oxidizing agent so that just aboutthe theoretically requisite quantity (one equivalent per mol oi.beta-anthraquinone-sultonic acid) is fed in during the reaction period.For best results, the oxidizing agent should be 'fed in at such a ratethat a sample oi the reaction mixture at any stage except at the veryend should contain some leuco derivatives of anthraquinone, but at nostage should it contain reduction derivatives lower than leuco.

For the purpose of facilitating feeding the oxidizing agent into thehigh pressure autoclave, we prefer to use the same in the form oi: asolution or suspension in a liquid. For the further purpose offacilitating the separation of the final product from the oxidizingagent, we prefer to use a water soluble oxidizing agent, for instance,sodium, potassium or ammonium chlorate or bromate. Nitro-bemcene, itssultonic acids or their salts may also be added if desired or expedient,as the disadvantages arising from the use of these substances in theprocesses pointed out above, are overcome in this process be cause ofthe fact that a high concentration of these compounds is never presentin the reaction mixture.

The following exan'iplc in which parts by weight are given serves morefully to illustrate our invention.

E war-771]) lo 310 parts of the sodium saltol':anthraqlinlone-beta-sulfonic acid are charged into an autoclavecontaming 2000 parts of 25% aqueous ammonia (250 gm. per liter). Theautoclave is closed and brought to a temperature of about 175 C. withina period of 3 to l hours, and maintained at this temperature for another3 hours. The pressure at this point is about 580 pounds per square inch.A solution of 50 parts of sodium chlorate in. 300 parts of 25% aqueousammonia is then slowly introduced into the vessel at such a rate that itis all added in a period of about 15 to 18 hours, the temperature beingmaintained. at about 175 C. The mass is held at this temperature for anadditional two hours and then cooled to room temperatitire. Theautoclave is now opened and sutiicient water added to bring the totalvolume to that corresponding to about 6000 parts by weight. 7 0 ia'rtsof caustic soda are next added and the resulting mass heated until freeof ammonia. The hot suspension is filtered and Washed with water. Thebeta-amino-anthraquinone thus obtained is in substantially pure form,and when. dry is a reddish orange powder melting at about 306 to 308 C.The yield is over of theory It will, of course, be understood. that thisprocess may be varied within wide limits.

Without departing from the spirit of our invention. Thus, thetemperature of the reaction may range anywhere from 160 to 210 C.Further, the concentration of the ammonia may be varied from 10 to 35%,using correspondingly lower or higher pressures. Similarly, instead ofusing precisely 1 equivalent of oxidizing agent per mol ofbetaanthraquii'ione-sul'l onic acid, an excess or deficiency of the samemay be employed, for instance, 0.75 to 2.00 equivalents per mol of theanthraquinone compound. In the case of an excess, however, the bestresults will not be obtained unless care is taken to prevent the excessfrom being present in the mixture until most of thebeta-anthraquinone-sultonic acid has been converted over into the aminocompound. Again, the duration of the heating may vary from 5 hours orless to 24 hours or more. The addition of the oxidizing agent, moreover,may be extended over the entire reaction period or only over a majorportion thereof. As pointed out, however, better results are obtainedwith the slower rates of addition of said oxidizing agent.

Instead of the sodium salt of anthraquinone-beta-sulfonic acid, otherwater soluble salts of the same may be used, as well as the free acid.It is advantageous, however, to employ either the free acid, or suchsalts as do not form insoluble sulfates, chlorides, or hydroxides, forin such a case, the resultant beta-21mino-anthraquinone is obtained freeof inorganic impurities. In the claims below, the term abeta-anthraquinone-sultonic acid compound, should be understood to referto beta-anthraquinone-sultonic acid or its watersoluble salts; the termalkali-metal salt should be understood as comprising the sodium,potassium or ammonium salts.

l/Ve claim as our invention:

1. In the process of preparing beta-aminoanthraquinone by treating abeta-anthraquinone-sulfonic acid compound with ammonia, the steps whichcomprise first bringing a mixture of these reactants to the reactiontemperature and pressure and then adding an oxidizing agent thereto.

2. In the process of preparing beta-aminoanthraquinone by treating abeta-anthraquinone-sulfonic acid compound with ammonia, the steps whichcomprise heating a mix ture of these reactants under pressure to thereaction temperature, permitting the reaction to proceed for some time,and then add ing an oxidizing agent to the reaction mass.

In the process of preparing beta-aminoanthraquinonc by treating abeta-anthraquinone-sulfonic acid compound with ammonia, the step whichcomprises adding an oxidizing agent to the reaction mixture while thesame is under reactive conditions at a rate insufi'icient to prevent theformation within the mixture of anthraquinone leuco compounds butsufiicient to prevent the formation of reduction products lower than theleuco during the maj or portion of the reaction period.

4. In the process of preparing beta-amino anthraquinone by treating abeta-anthraquinone-sulfonic acid compound with ammonia, the step whichcomprises adding an oxidizing agent to the reaction mixture at a ratenot substantially higher than the rate of formation of sulfurous acidcompounds therein.

5. The process of preparing beta-aminoanthraquinone which comprisesslowly heating a mixture of an alkali metal salt ofanthraquinone-beta-sulfonic acid and an aqueous solution of ammonia toabout 175 C. in an autoclave, maintaining this temperature for aboutthree to four hours and then gradually adding a solution of an alkalimetal chlorate over a prolonged period while maintaining saidtemperature of 175 C. in the autoclave.

6. In the process of preparing beta-aminoanthraquinone by treating abeta-anthraquinone-sulfonic acid compound with aqueous ammonia, thesteps which comprise first bringing a mixture of these reactants to thereaction temperature and pressure and then adding an oxidizing agentthereto.

7. In the process of preparing beta-aminoanthraquinone by treating abeta-anthraquinone-sulfonic acid compound with aqueous ammonia, thesteps which comprise heating a mixture of these reactants under pressureto the reaction temperature, permitting the reaction to proceed for sometime, and then adding an oxidizing agent to the reaction mass.

8. In the process of preparing beta-aminoanthraquinone by treating abeta-anthraquinone-sulfonic acid compound with an aqueous solution ofammonia, the step which comprises adding an oxidizing agent to thereaction mixture while the same is under reactive conditions at a rateinsufficient to prevent the formation within the mixture ofanthraquinone leuco compounds but suflicient to prevent the formation ofreduction proclucts lower than the leuco during the major portion of thereaction period.

9. In the process of preparing beta-aminoanthraquinone by treating abeta-anthraquinone-sulfonic acid compound with an excess of an aqueousammoniacal solution, the step which comprises adding an oxidizing agentto the reaction mixture at a rate not substantially higher than the rateof formation of sulfurous acid compounds therein.

In testimony whereof we have hereunto subscribed our names atCarrollville, lwilwaukee County, Wisconsin.

IVAN GUBELMANN. JOHN M. TIN KER.

